Extruded cylinder with a solid wood exterior shell

ABSTRACT

An architectural unit having an extruded core of wood fiber and a thermoset resin, the extruded core having a central hole coaxial with a major axis of the core and an exterior; a plurality of shaped staves forming a shell, each stave of the plurality of staves disposed about the exterior of the core and parallel to the major axis.

RELATED APPLICATIONS

This application is a Continuation of U.S. Utility application Ser. No.12/328,800, filed Dec. 5, 2008, which claims the benefit of U.S.Provisional Application No. 60/992,350, filed Dec. 5, 2007, both ofwhich are herein incorporated in its entirety by reference.

FIELD OF THE INVENTION

The invention relates to a structural core or bolt, and moreparticularly, to an extruded wood fiber core with an applied solid woodexterior shell.

BACKGROUND OF THE INVENTION

Wood fiber cores have been used in applications utilized for winding orspooling industrial products. Extruded wood fiber cores, such as thosemanufactured by the assignee since the mid 1960's, have been suitablefor applications where low cost is valued, and where durability is notessential. Wood fiber cores have excellent compressive strength in theaxial direction, but only moderate or poor tensile strength in thetransverse direction. Such fiber cores may be extruded or molded. Woodfiber cores are typically limited to single use as they lack beamstrength, and unwinding of materials from the core can produce cracks,fissures or other structural defects rendering them inoperative.

Solid wood cores are manufactured using labor intensive machining oflumber, gluing, clamping and various steps. While more expensive thanextruded core, the solid wood provides improved structural integrity forheavier materials or multiple use applications. Such solid wood coresare of particular value in intracompany uses. Such solid wood cores haveimproved beam strength.

Similarly, the steel cores are highly durable, but require expensivefabrication and welding, are heavy, and are expensive to ship.

What is needed, therefore, are techniques for providing durable,reusable cylinders manufacturable with low labor.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a method for theproduction of structural cores with a solid wood exterior, the methodcomprising: providing a extruded wood core column; providing a pluralityof solid wood staves having an interior profile mating an exteriorprofile of the extruded wood column; applying an adhesive to theinterior profile of the staves and the exterior profile of the core;adhering the interior profile of each of the staves to the exteriorprofile of the core; mechanically securing the staves to the core;allowing the adhesive to cure providing a structural core with a solidwood exterior.

Another embodiment of the present invention provides such a methodfurther comprising placing at least one steel band about an end of thestructural core with the solid wood exterior and embedding the band inthe solid wood exterior.

A further embodiment of the present invention provides such a methodfurther comprising disposing at least one end cap on an end of thestructural core with the solid wood exterior and crimping the end cap tosecure it to the structural core with the solid wood exterior.

Yet another embodiment of the present invention provides such a methodwherein the step of mechanically securing comprises nailing the stavesto the extruded core.

A yet further embodiment of the present invention provides such a methodwherein the step of mechanically securing comprises clamping the stavesto the extruded core.

Still another embodiment of the present invention provides such a methodfurther comprising machining the staves from wood of a variety selectedfrom the group of wood varieties consisting of poplar, oak, ash, maple,mahogany, and walnut.

A still further embodiment of the present invention provides such amethod wherein the wood is an exotic species of wood.

Even another embodiment of the present invention provides such a methodfurther comprising fluting the staves.

An even further embodiment of the present invention provides such amethod further comprising shaping the staves such that the solid woodexterior is tapered.

Still yet another embodiment of the present invention provides such amethod wherein the solid wood exterior comprises a parabolic frustrum.

One embodiment of the present invention provides a structural unit; thestructural unit comprising: a extruded core comprising wood fiber and athermoset resin having a central hole coaxial with a major axis of thecore and an exterior; a plurality of shaped staves forming a shell, eachstave of the plurality of staves disposed about the exterior of the coreand parallel to the major axis.

Another embodiment of the present invention provides such a structuralunit further comprising at least one slot disposed in at least one thestave is provided parallel to the axis.

A further embodiment of the present invention provides such a structuralunit wherein the plurality of staves form a cylindrical shell around thecore.

Yet another embodiment of the present invention provides such astructural unit wherein shell has groves where the staves meet.

A yet further embodiment of the present invention provides such astructural unit wherein the staves are manufactured from a wood, thewood being of a wood species selected from the group of speciesconsisting of poplar, pine, oak, mahogany and walnut.

Still another embodiment of the present invention provides such astructural unit wherein the staves are tapered, such that the stavesform a smooth, longitudinally tapered shell around the core.

A still further embodiment of the present invention provides such astructural unit, wherein the shell is fluted.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and not to limit the scope ofthe inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective drawing illustrating an extruded core cylinderwith a solid wood shell configured in accordance with one embodiment ofthe present invention.

FIG. 2A is a top plan view drawing illustrating a smooth stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 2B is an elevation view drawing illustrating a smooth stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 2C is a bottom plan view drawing illustrating smooth stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 3A is a top plan view drawing illustrating a fluted stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 3B is an elevation view drawing illustrating a fluted stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 3C is a bottom plan view drawing illustrating a fluted stave of anextruded core cylinder with a solid wood shell configured in accordancewith one embodiment of the present invention.

FIG. 4 is a cross sectional plan view illustrating an extruded corecylinder with a solid wood shell configured in accordance with oneembodiment of the present invention and having a spiraled cross section.

FIG. 5 is a cross sectional plan view illustrating an extruded corecylinder with a solid wood shell configured in accordance with oneembodiment of the present invention and having retention slots disposedin the solid wood shell.

FIG. 6 is an elevation view illustrating an extruded core cylinder witha solid wood shell configured in accordance with one embodiment of thepresent invention having a retention slot.

FIG. 7 is a perspective view illustrating an extruded core cylinder forsheathing with a solid wood shell configured in accordance with oneembodiment of the present invention.

FIG. 8 is an elevation view illustrating an extruded core cylinder witha solid wood shell configured in accordance with one embodiment of thepresent invention undergoing clamping.

DETAILED DESCRIPTION

As illustrated in FIG. 1, a cylinder 12 of extruded wood fiber disposedin a resin matrix is provided by one embodiment of the presentinvention. The extruded core 12 is covered in a shell 18 of woodenstaves 14. In one embodiment of the present invention, each stave 14covers one eighth of the circumference of the extruded core 12. Staves14, according to one embodiment of the present invention, are glued tothe exterior of the extruded core 12. Nails may be used to affix thestaves 14 to the core 12 while the glue cures, and may add additionalstrength to the bond between the staves 14 and the core 12. Duringmanufacture, staves 14 may be clamped to the core 12 to insure propercuring of the adhesive manually, using pipe clamps or other suitablehand clamp with a circular pressure ring, or may be clamped using aautomated device whereby pressure is applied to the circumference of thestave shell. In one such embodiment pneumatic pressure may be applied,such as by an air choke. For example, Air Flex® clutch break single anddouble flange elements, part no. 142197JA sold by Eaton Corporation maybe used. A central extruded bore 16 is provided through the core 12 topermit the introduction of shafts or other mounting means as necessary.Staves 14 are illustrated in greater detail in FIGS. 2A-3C.

In one embodiment of the present invention, illustrated in FIG. 6 a slot22 may be machined in one or more of the staves to allow theintroduction of a tongue or anchor into the roll so as to facilitate theanchorage of the material to be wound upon the roller to the roller.Alternative retention means, including a spiraled cross section and aplurality of retention slots are illustrated in FIGS. 4 and 5,respectively.

In one embodiment of the present invention, and end cap may be placedover each of the ends of a completed composite core thereby providingimproved radial strength. Such caps are known to those skilled in theart and are used with known solid wood cores. In alternative embodimentswhere such strength is unimportant, such an endcap is unnecessary.

In one embodiment of the invention, the staves 14 may be configured withan exterior profile such that when each stave 14 is applied to the core12 such that the elongate length of the stave 14 is parallel to the axisof the core 12, the exterior profile of the stave is rounded to form anarc, and the arcs of the eight staves combine to form a circular crosssection. In alternative embodiments where the core may be used asstructural or aesthetic architectural element, the staves may bemachined prior to application to provide a suitable taper to the column,as illustrated in FIGS. 2A-2C, or in some embodiments fluting asillustrated in FIGS. 3A-3C. Such a taper may be obtained by applying a“shoe” to the stave during machining. In such esthetic embodiments, thestaves may be applied to the core without nails, so as to avoid marringthe surface of the lumber; alternatively an additional step may beemployed wherein nail holes are filled with wood putty prior to sandingand finishing. One skilled in the art can appreciate that suitablecapitals or other ornamental end pieces may be applied.

The interior profile of each stave 14, in one embodiment is curved toprovide optimum contact with the exterior surface of an extruded corehaving a circular cross section. As noted above, in one embodiment,staves may comprise eight staves disposed about the circumference of theextruded core, while in alternative embodiments; different numbers ofstaves may be employed. Similarly, various cross-sectional shapes may beimparted to the extruded cores. In alternative embodiments whereextrusions of square, polygonal, pentagonal, hexagonal, heptagonal,octagonal, nonagonal, or decagonal cross section or cross sections ofany number of sides, staves with flat interior sides may be provided. Insuch embodiments same number of staves as of sides may be used.Similarly, in other alternative embodiments, staves may be milled tomatch the profile of the extruded core. It is noted, however, thatpolygonal cross sections can reduce the waist rate of the milled stavesas the milled stave need only be milled on the exterior.

Wood used in the construction of staves may, in one embodiment be woodfrom trees of the genus Populus. Other inexpensive, easily milled, woodsmay be used. The density of the wood may likewise be selected based uponfactors including the desired durability of the unit produced, theweight and strength requirements, and a need for relative flexibilitymay be considered. Other suitable woods may include softwoods such aspine or hardwoods such as oak or maple. Exotic species, like mahogany,rosewood, and teak may also be used in applications where the estheticsof the finished piece require such woods.

Glues used in the adhesion of the staves to the core are chemically andstructurally compatible with the resins used in the core. Degradation ofthe core could compromise strength of the system. In one embodiment woodglue, such as that available under the trademarks Elmer's and Tightbondmay be used. Alternatively, resins similar to or identical with thatused in the wood fiber extrusion may be used. In one such embodimentboth the extrusion and the glue are Urea-Formaldehyde resins. Thesetting of the Urea-Formaldehyde resin may be accelerated usingcatalysts. Examples of catalysts used include various metal salts, suchas aluminum sulfate.

In one embodiment of the present invention, first and second bands 20are disposed about first and second ends of the shell 18. In oneembodiment these bands may be configured from steel or other suitable,high tensile strength material. These bands 20 may be disposed inrabbeted channels disposed in the shell 18. Alternatively, thetightening of the bands 20 may depress the wood staves sufficiently tokeep the steel band 20 from contacting items coiled about the shell 18.The ends of the bands 20 may be crimped or buckled to ensure a secureand low profile joint. In some embodiments, the crimp or buckle may berecessed in a receiving recess.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and variations are possible in light ofthis disclosure. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

1. An architectural unit; said architectural unit comprising: anextruded core comprising wood fiber and a thermoset resin having acentral hole coaxial with a major axis of said core and an exterior; aplurality of shaped staves forming a shell, each stave of said pluralityof staves disposed about the exterior of said core and parallel to saidmajor axis.
 2. The architectural unit of claim 1 further comprising atleast one slot disposed in at least one said stave is provided parallelto said axis.
 3. The architectural unit of claim 1 wherein saidplurality of staves forms a cylindrical shell around said core.
 4. Thearchitectural unit of claim 3 wherein shell has groves where said stavesmeet.
 5. The architectural unit according to claim 1 wherein said stavesare manufactured from a wood, said wood being of a wood species selectedfrom the group of species consisting of poplar, pine, oak, mahogany andwalnut.
 6. The architectural unit according to claim 1 wherein saidstaves are tapered, such that said staves form a smooth, longitudinallytapered shell around said core.
 7. The architectural unit of claim 1,wherein said shell is fluted.